The present invention relates, in general, to the formation of elastic bands and, more particularly, relates to the cutting of elastic bands from tubular band stock and the unbonding or separating of the sides or cut edges of the bands after cutting.
Elastic or rubber bands are formed from various combinations of synthetic and natural rubbers and filler materials. The fillers are used to provide the elastic bands with a variety of properties, and more particularly, they also are used to control the elasticity or elongation of the bands. Generally, as the percentage of fillers increase, the band elasticity decreases, and conversely the most elastic of the elastic bands are virtually entirely formed from synthetic or natural rubber.
While there are many applications in which a highly elastic, (e.g., 300 to 800 percent elongation) elastic band is desirable, there are serious problems in the formation and manipulation of such bands. Most typically, elastic bands are cut from tubular elastic band stock having a diameter equal to the desired band length in the relaxed condition. Cutting can be effected by a fly cutter, particularly for narrow widths, or a scissors-type of cutter.
In prior art elastic band cutting apparatus the bands are usually simply cut and then collected. Thus, the cutting apparatus merely deposits the bands in a jumble in a collecting bin with a random orientation. For bands which have a high degree of elastomeric compounds, the cutting process also often bonds or welds the opposite sides of the bands together. This bonding is particularly common for the scissor-type of cutting apparatus.
Attempts have been made to try to separate the bonded edges of elastic bands. One approach is simply agitation of the jumbled collection of cut bands. Another approach is to employ suction apparatus which engages and vacuum grips opposite sides of the bonded band during or immediately after the cutting process. The vacuum gripping units are then separated while the vacuum is applied to attempt to pull the sides of the bands apart and break the bonds created during cutting.
Such vacuum unbonding apparatus has been found to have limited effectiveness. First, it is best employed with relatively wide elastic bands. Second, the vacuum is often broken before the bond between the cut edges of the band is broken. Lastly. after separation, the bands are usually deposited in a collector in random orientations so that subsequent use of the bands requires a band sorting and orienting apparatus.
While apparatus have been evolved for the extraction of individual rubber bands from a randomly oriented collection of rubber bands, such apparatus usually severely limit the speed with which bands can be applied to an end use. Thus, cutting apparatus typically produces cut elastic bands much faster than band sorting and orienting apparatus can extract and orient bands from a pile of randomly oriented bands. The problems of sorting and orienting bands become even more severe as the band width decreases and as the band elasticity increases.